Organic electroluminescent device

ABSTRACT

Disclosed is an organic electroluminescent device including a substrate, a first and a second electrode, and an emitting layer formed between the first electrode and the second electrode. The emitting layer includes a plurality of materials which is a blue emitting material using a following chemical formula as dopant.  
                 
 
     In this case, at least one of A 1  and A 2  is selected from a substituted or non-substituted aromatic group, a heterocyclic group, an aliphatic group, and hydrogen.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Application Nos.P2002-83279 filed on Dec. 24, 2002 and P2003-20465, filed on Apr. 1,2003, which are hereby incorporated by references as if fully set forthherein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an organic luminescent device,and more particularly, to a blue emitting material of an emitting layer.

[0004] 2. Description of the Related Art

[0005] Recently, with the trend of a large sized display, a request of aflat display that occupies a small area has been increased. One exampleof the flat display is an organic electroluminescent device also calledas an organic light emitting diode (OLED). And, technology for theorganic electroluminescent display is developed rapidly, whereby variousprototypes have been in market already.

[0006] The organic electroluminescent device emits light in a mannerthat electric charges are injected in an organic layer formed between ananode and a cathode so as to form a pair of electron and hole togenerate an exciton and an excited state of the exciton falls to aground state so as to emit light.

[0007] The organic electroluminescent device is not only formed on aflexible transparent substrate such as a plastic but also operated at alower voltage (less than 10V) compared to a plasma display panel or aninorganic electroluminescent display.

[0008] Also, the organic electroluminescent device has advantages inthat power consumption is reduced and various colors are available.

[0009] Moreover, the organic electroluminescent device enables toexpress three colors including green, blue, and red. Therefore, manyconcerns are focused on the organic electroluminescent device as thenext generation full color display.

[0010] The organic electroluminescent device may be realized to emitblue, green, or red light in accordance with a material forming theemitting layer.

[0011] Particularly, the emitting layer for blue luminescence is a hostemploying materials such as PBD and DPVBi and is fabricated by doping1-3% of materials such as perylene, coumarine, and pyrene as a dopant.

[0012] However, it is a biggest problem in realizing blue luminescenceof the organic electroluminescent device that a degree of color purityand the luminescence efficiency are lowered.

[0013] The conventional blue emitting materials emit light with a longwavelength during emission and had a problem of lowering the degree ofcolor purity and the luminescence efficiency, and even more lowered athigh doping density.

SUMMARY OF THE INVENTION

[0014] Accordingly, the present invention is directed to an organicelectroluminescent device that substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

[0015] An object of the present invention is to provide an organicelectroluminescent device.

[0016] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

[0017] To achieve these objects and other advantages and in accordancewith the purpose of the invention, as embodied and broadly describedherein, an organic luminescent device includes a substrate; a first andsecond electrodes formed on the substrate; an emitting layer formedbetween the first electrode and the second electrode, the emitting layerhaving a plurality of materials and being a blue emitting material usinga chemical formula 1 as a dopant.

[0018] In this case, at least one of A₁ and A₂ is selected from asubstituted or non-substituted aromatic group, a heterocyclic group, analiphatic group, and hydrogen.

[0019] Wt. % of the material in the chemical formula 1 is 0.1-49.9 wt. %of a total weight of the emitting layer.

[0020] Material forming the emitting layer together with the material ofthe chemical formula 1 is formed as a structure of a following chemicalformula 2.

B1-X-B2  [Chemical formula 2]

[0021] Wherein, the X is selected from a group consisting ofnaphthalene, anthracene, phenanthrene, pyrene, perylene, and quinolineand at least one of the B1 and B2 is selected from a group consisting ofaryl, alkylaryl, alkoxyaryl, arylaminoaryl and alkylaminoaryl.

[0022] At least one of the B1, B2 is selected from phenyl, biphenyl,pyridyl, naphthyl, tritylphenyl, biphenylenyl, anthryl, phenanthryl,pyrenyl, perylenyl, quinolyl, isoquinolyl, fluorenyl, terphenyl, tolyl,xylyl, methylnaphthyl, and hydrogen.

[0023] At least one of the A1 and A2 is selected from a substituted ornon-substituted phenyl, a substituted or non-substituted biphenyl, asubstituted or non-substituted pyridyl, a substituted or non-substitutednaphthyl, a substituted or non-substituted quinolyl, a substituted ornon-substituted isoquinolyl, a substituted or non-substituted fluorenyl,a substituted or non-substituted terphenyl, methyl, ethyl, propyl,i-propyl, and t-buthyl.

[0024] The substituent of each substituted A1 and A2 is at least one andselected from methyl, ethyl, propyl, i-propyl, t-butyl, cyclohexyl,methoxy, ethoxy, propoxy, butoxy, dimethylamino, trimethylsilyl,fluorine, chroline, phenoxy, tolyloxy, dimethylamino, diethylamino,diphenylamino, and triphenylsilyl.

[0025] It is to be understood that both the foregoing generaldescription and the following detailed description of the presentinvention are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed.

DETAILED DESCRIPTION OF THE INVENTION

[0026] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

[0027] In the present invention, the emitting layer formed between afirst electrode and a second electrode includes a plurality of materialsand a blue material using a following chemical formula as a dopant.

[0028] In this case, at least one of A₁ and A₂ is selected from asubstituted or non-substituted aromatic group, a heterocyclic group, analiphatic group, or hydrogen.

[0029] A wt. % of the material in the chemical formula 1 is 0.1˜49.9 wt% among a total weight of the emitting layer. The material forming theemitting layer with the chemical formula 1 is formed as a structure of afollowing chemical formula 2.

B1-X-B2  [Chemical formula 2]

[0030] In this case, X is selected from a group consisting ofnaphthalene, anthracene, phenanthrene, pyrene, perylene, amd quinoline.At least one of the B1 and B2 may be selected from a group consisting ofaryl, alkylaryl, alkoxyaryl, arylaminoaryl and alkylaminoaryl.

[0031] Also, at least one of the B1 and B2 may be selected from a groupconsisting of phenyl, biphenyl, pyridyl, naphthyl, tritylphenyl,biphenylenyl, anthryl, phenanthryl, pyrenyl, perylenyl, quinolyl,isoquinolyl, fluorenyl, terphenyl, tolyl, xylyl, methylnaphthyl, andhydrogen.

[0032] In this case, the material forming the emitting layer togetherwith the chemical formula 1 is one of following chemical formulas.

[0033] Also, in a case of the chemical formula 1, at least one of the A1and A2 may be selected from a substituted or non-substituted aromaticgroup, a heterocyclic group, an aliphatic group, and hydrogen.

[0034] Particularly, at least one of A1 and A2 may be selected from asubstituted or non-substituted phenyl, a substituted or non-substitutedbiphenyl, a substituted or non-substituted pyridal, a substituted ornon-substituted naphthyl, a substituted or non-substituted quinolyl, asubstituted or non-substituted isoquinolyl, a substituted ornon-substituted fluorenyl, a substituted or non-substituted terphenyl,methyl, ethyl, propyl, i-propyl, and t-buthyl.

[0035] In this case, each substituent of the substituted A1 and A2 is atleast one and selected from alkyl, alkoxy, alkylamino, alkylsilyl,halogen, aryl, aryloxy, arylamino, arylsilyl, and hydrogen.

[0036] For example, the substituent of the A1 and A2 may be selectedfrom methyl, ethyl, propyl, i-propyl, t-butyl, cyclohexyl, methoxy,ethoxy, propoxy, butoxy, dimethylamino, trimethylsilyl, fluorine,chlorine, phenoxy, tolyloxy, dimethylamino, diethylamino, diphenylamino,and triphenylsilyl.

[0037] Particularly, at least one of the substituted or non-substitutedA1 and A2 may be one of the following chemical formulas.

[0038] The blue emitting material having the substituent of the presentinvention may be one of the following chemical formulas.

[0039] According to the organic electroluminescent device,N,N′-Bis-(4-tert-butyl-phenyl)-N,N′-di-pyridin-2-yl-pyrene-1,6-diamineemployed as the blue emitting material is compounded as follows.

[0040] (1) Synthesis of 1,6-Dibromopyrene

[0041] First, pyrene (10 g, 0.0049 mol) is dissolved into CCl₄ (300 mL)in a 3-necks-r.b.f. And, Br₂ (17.38 g, 0.108 mol)

CCl₄ (50 mL) are put into a dropping funnel provided at the round-floorflask and slowly dropped in the round-floor flask for 4 hours. N₂ isadded to and HBr is removed from the solution. When the process isfinished, the solution is stirred under N₂ current for one hour andformed sediment is filtered.

[0042] When the sediment is recrystallized by toluene, a green solidmatter (6.05 g, 34%) of 1,6-Dibromopyrene and a white solid matter of1,8-Dibromopyrene (5 g, 28%) are obtained.

[0043] (2) Synthesis of N,N,N′,N′-Tetraphenyl-pyrene-1,6-diamine

[0044] First, 1,6-Dibromopyrene (3 g, 0.0083 mol), Diphenylamine (4.23g, 0.025 mol), BINAP ([2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl])(0.052 g, 1% mol), Pd(OAC)₂[Palladium(II)acetate](0.019 g, 1% mol) andNaO^(t)Bu[Sodium tert-butoxide](2.3 g, 0.029 mol) are dissolved intotoluene (80 mL) in 2-necks-r.b.f. so as to be refluxed.

[0045] When the reaction is finished, the 2-necks-r.b.f. is cooled at anormal temperature and about 40 ml of toluene, that is, a reactionsolvent is removed by distillation under reduced pressure.

[0046] When methanol (100 ml) is added to the solution from whichtoluene 40 ml is removed, sediment is generated.

[0047] When the sediment is filtered, a yellow solid matter ofN,N,N′,N′-Tetraphenyl-pyrene-1,6-diamine (3.22 g, 72%) is obtained.

[0048] (3) Synthesis of (4-Bromo-phenyl)-trimethyl-silane

[0049] First, a dropping funnel is provided at the 3-necks-r.b.f and theround-floor flask is dried under decompression. 1,4-Dibromobenzene (12.7g, 0.053 mol) and the dried diethylether (300 mL) are dissolved in theround-floor flask.

[0050] A dryice bath is provided at the round-floor flask, n-BuLi (33.58mL, 0.0537 mol) is put into the dropping funnel and n-BuLi is slowlydropped, and a temperature is slowly raised from −78° C. to 0° C.

[0051] Next, chloro trimethylsilane (7.51 mL, 0.059 mol) is slowlydropped at 0° C. and then the temperature is raised again to the normaltemperature for over a period of one hour.

[0052] When the reaction is finished, sediment is extracted by usingdiethylether and water is removed from the result by using MgSO₄.

[0053] And then, after solvent is removed from the result, when thesolvent is fractionally distilled under decompression,(4-Bromo-phenyl)-trimethyl-silane (11.3 g, 92%) is obtained.

[0054] (4) Synthesis of(4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl)-amine

[0055] 4-tert-Butyl-phenylamine (1.2 mL, 0.0076 mol),(4-Bromo-phenyl)-trimethyl-silane (1 g, 0.0044 mol), BINAP (0.03 g, 1%mol), Pd(OAc)₂ (0.01 g, 1% mol) and NaO^(t)Bu (1.5 g, 0.016 mol) aredissolved into toluene (50 mL) in the 2-necks-r.b.f. so as to berefluxed for about 2 hours.

[0056] When the reaction is finished, the 2-necks-r.b.f. is cooled andtoluene, which is reaction solvent, is removed.

[0057] Next, when the sediment is filtered, the white solid matter suchas (4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl)-amine (1.12 g, 86%)is obtained.

[0058] (5) Synthesis ofN,N′-Bis-(4-tert-butyl-phenyl)-N,N′-bis-(4-trimethylsilanyl-phenyl)-pyrene-1,6-diamine

[0059] (1,6-Dibromopyrene) (0.787 g, 0.0022 mol),(4-tert-Butyl-phenyl)-(4-trimethylsilanyl-phenyl)-amine) (1.56 g,0.00525 mol), BINAP (0.054 g, 4% mol), Pd(OAc)₂ (0.015 g, 3% mol) andNaO^(t)Bu (0.93 g, 0.0096 mol) are dissolved in toluene (40 mL) so as tobe refluxed for 24 hours.

[0060] When reaction is finished, the round-floor flask is cooled andresult material is extracted by using water and methylene chloride aftertoluene, that is, the reaction solvent is removed.

[0061] And then, water is removed from the result by using MgSO₄ andmethylene chloride is removed by decompression, and silica gelchromatography is separated by using n-hexane:methylene chloride (6:1).

[0062] When the solvent is removed from the result and a solid matter isfiltered by using nucleic acid, yellow solid matter such as(N,N′-Bis-(4-tert-butyl-phenyl)-N,N′-bis-(4-trimethylsilanyl-phenyl)-pyrene-1,6-diamine)(1.09 g, 63%) is obtained.

[0063] (6) Synthesis ofN,N′-Diphenyl-N,N′-di-pyridin-2-yl-pyrene-1,6-diamine

[0064] (1,6-Dibromopyrene) (1.2 g, 0.0033 mol),(Phenyl-pyridin-2-yl-amine) (1.36 g, 0.008 mol), BINAP (0.083 g, 4%mol), Pd(OAc)₂ (0.022 g, 3% mol) and NaO^(t)Bu (1.28 g, 0.013 mol) aredissolved in toluene (50 mL) in the 2-necks-r.b.f so as to be refluxedfor 24 hours.

[0065] When the reaction is finished, solid matter is generated.

[0066] When 50% of toluene is removed from the solid matter, andmethanol (70 ml) is added to the solid matter, which then is filtered,yellow solid matter(N,N′-Diphenyl-N,N′-di-pyridin-2-yl-pyrene-1,6-diamine) (0.81 g, 45%) isobtained.

[0067] (7) Synthesis of (4-terr-Butyl-phenyl)-pyridin-2-yl-amine

[0068] (4-tert-Butyl-phenylamine) (1.2 mL, 0.0076 mol), (2-Bromopyridine) (1 mL, 0.01 mol), BINAP (0.06 g, 4% mol), Pd(OAc)₂ (0.02 g, 3%mol) and NaO^(t)Bu (1.5 g, 0.016 mol) are dissolved in toluene (50 mL)in the 2-necks-r.b.f. so as to be refluxed for 24 hours.

[0069] When the reaction is finished, the 2-necks-r.b.f. is cooled andtoluene, that is, reaction solvent is removed. Result material isextracted by using water and methylene chloride. methylene chloride isremoved under decompression after water is removed by using MgSO₄.

[0070] Silica gel short column is generated by methylene chloride,sediment is formed by using nucleic acid. When the sediment is filtered,white solid matter such as 4-tert-Butyl-phenyl)-pyridin-2-yl-amine (1.32g, 73%) is obtained.

[0071] (8) Synthesis ofN,N′-Bis-(4-tert-butyl-phenyl)-N,N′-di-pyridin-2yl-pyrene-1,6-diamine

[0072] 1,6-Dibromopyrene (1 g, 0.0028 mol),(4-tert-Butyl-phenyl)-pyridin-2-yl-amine (1.51 g, 0.0067 mol), BINAP(0.07 g, 4% mol), Pd(OAc)₂ (0.02 g, 3% mol)

NaO^(t)Bu (1.18 g, 0.012 mol) are dissolved in toluene (45 mL) in the2-necks-r.b.f. so as to be refluxed for 24 hours.

[0073] When the reaction is finished, solid matter is generated. 50% oftoluene is removed from the solid matter, which is then filtered aftermethanol (70 mL) is added thereto. When the solvent is removed by silicagel short column by using methylene chloride,(N,N′-Bis-(4-tert-butyl-Phenyl)-N,N′-di-pyridin-2-yl-pyrene-1,6-diamine)(0.99 g, 60%) is obtained.

[0074] Hereinafter, a preferred embodiment of the organicelectroluminescent device will be described according to the presentinvention.

[0075] [Embodiment]

[0076] An ITO glass is patterned so as to have a size of 3 mm×3 mm. Thepatterned ITO glass is then cleaned.

[0077] A substrate is loaded on a vacuum chamber of which basic pressureis set up as 1×10⁻⁶ torr, CuPC (200 Å), NPB (500 Å), a light-emittinglayer (300 Å), Alq₃ (500 Å), LiF (5 Å), and Al (1,000 Å) are depositedon the ITO in order.

[0078] In this case, material in a following drawing is employed as afirst HOST of the emitting layer and a mixing ratio of the host anddopant is 1:0.01.

[0079] [First Embodiment]

[0080] When about 1 mA of electric current is flown by using dopanthaving a chemical formula of S-26, brightness shows about 3.2 cd/A,whereby CIE (Commision Internationale de L'Eclairage) x=0.146, y=0.205.

[0081] [Second Embodiment]

[0082] When about 1 mA of electric current is flown by using dopanthaving a chemical formula of S-28, brightness shows about 3.4 cd/A,whereby CIE (Commision Internationale de L'Eclairage) x=0.15, y=0.196.

[0083] [Comparative Embodiment]

[0084] ITO (Indium Tin Oxide) glass is patterned so as to have a size of3 mm×3 mm. The patterned ITO glass is then cleaned.

[0085] A substrate is loaded on a vacuum chamber of which basic pressureis set up as 1×10⁻⁶ torr, and such an organic matters as CuPC (200 Å),NPB (500 Å), emitting layer (300 Å), Alq₃ (200 Å), LiF (5 Å), and Al(1000 Å) are deposited on the ITO glass.

[0086] When about 1 mA of electric current is flown, brightness is about1.8 cd/A, whereby CIE (Commision Internationale de L'Eclairage) x=0.15,y=0.196.

[0087] Accordingly, the present invention is a blue emitting material ofan emitting layer and an organic elecroluminescent device with bluecolor purity and a high luminescent efficiency is obtained by materialwith high color purity.

[0088] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic electroluminescent device, comprising:a substrate; a first and second electrodes formed on the substrate; anemitting layer formed between the first electrode and the secondelectrode, the emitting layer having a plurality of materials and beinga blue emitting material using a chemical formula 1 as a dopant.

Wherein, at least one of A₁ and A₂ is selected from a substituted ornon-substituted aromatic group, a heterocyclic group, an aliphatic groupand hydrogen.
 2. The organic electroluminescent device of claim 1,wherein wt. % of the material in the chemical formula 1 is 0.1-49.9 wt.% of a total weight of the emitting layer.
 3. The organicelectroluminescent device of claim 1, wherein materials forming theemitting layer together with the material of the chemical formula 1 isstructured as a chemical formula
 2. B1-X-B2  [Chemical formula2]Wherein, the X is selected from a group consisting of naphthalene,anthracene, phenanthrene, pyrene, perylene, and quinoline and at leastone of the B1 and B2 is selected from a group consisting of aryl,alkylaryl, alkoxyaryl, arylaminoaryl and alkylaminoaryl.
 4. The organicelectroluminescent device of claim 3, wherein at least one of the B1 andB2 is selected from phenyl, biphenyl, pyridyl, naphthyl, tritylphenyl,biphenylenyl, anthryl, phenanthryl, pyrenyl, perylenyl, quinolyl,isoquinolyl, fluorenyl, terphenyl, tolyl, xylyl, methylnaphthyl, andhydrogen.
 5. The organic electroluminescent device of claim 1, whereinthe material forming the emitting layer together with the material ofthe chemical formula 1 is one of following formulas.


6. The organic electroluminescent device of claim 1, wherein at leastone of the A1 and A2 is selected from a substituted or non-substitutedphenyl, a substituted or non-substituted biphenyl, a substituted ornon-substituted pyridyl, a substituted or non-substituted naphthyl, asubstituted or non-substituted quinolyl, a substituted ornon-substituted isoquinolyl, a substituted or non-substituted fluorenyl,a substituted or non-substituted terphenyl, methyl, ethyl, propyl,i-propyl, and t-buthyl.
 7. The organic electroluminescent device ofclaim 1, wherein a substituent of each substituted A1 and A2 is at leastone and selected from alkyl, alkoxy, alkylamino, alkylsilyl, halogen,aryl, aryloxy, arylamino, arylsilyl and hydrogen.
 8. The organicelectroluminescent device of claim 7, wherein the substituent is oneselected from methyl, ethyl, propyl, i-propyl, t-butyl, cyclohexyl,methoxy, ethoxy, propoxy, butoxy, dimethylamino, trimethylsilyl,fluorine, chroline, phenoxy, tolyloxy, dimethylamino, diethylamino,diphenylamino, and triphenylsilyl.
 9. The organic electroluminescentdevice of claim 1, wherein at least one of the A1 and A2 in one offollowing chemical formulas.


10. The organic electroluminescent device of claim 1, wherein the blueemitting material is at least one of following chemical formulas.